全文获取类型
收费全文 | 97529篇 |
免费 | 593篇 |
国内免费 | 816篇 |
专业分类
98938篇 |
出版年
2023年 | 40篇 |
2022年 | 80篇 |
2021年 | 156篇 |
2020年 | 87篇 |
2019年 | 115篇 |
2018年 | 11940篇 |
2017年 | 10746篇 |
2016年 | 7608篇 |
2015年 | 848篇 |
2014年 | 556篇 |
2013年 | 627篇 |
2012年 | 4618篇 |
2011年 | 13229篇 |
2010年 | 12252篇 |
2009年 | 8424篇 |
2008年 | 10013篇 |
2007年 | 11645篇 |
2006年 | 498篇 |
2005年 | 728篇 |
2004年 | 1174篇 |
2003年 | 1197篇 |
2002年 | 922篇 |
2001年 | 289篇 |
2000年 | 174篇 |
1999年 | 40篇 |
1998年 | 35篇 |
1997年 | 39篇 |
1996年 | 27篇 |
1995年 | 6篇 |
1994年 | 16篇 |
1993年 | 36篇 |
1992年 | 21篇 |
1991年 | 43篇 |
1990年 | 10篇 |
1989年 | 11篇 |
1988年 | 17篇 |
1987年 | 13篇 |
1984年 | 8篇 |
1983年 | 19篇 |
1982年 | 5篇 |
1975年 | 6篇 |
1974年 | 3篇 |
1972年 | 247篇 |
1971年 | 276篇 |
1970年 | 6篇 |
1965年 | 13篇 |
1962年 | 24篇 |
1956年 | 5篇 |
1944年 | 12篇 |
1940年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
191.
Taxonomic distribution and origins of the extended LHC (light-harvesting complex) antenna protein superfamily 总被引:1,自引:0,他引:1
Background
The extended light-harvesting complex (LHC) protein superfamily is a centerpiece of eukaryotic photosynthesis, comprising the LHC family and several families involved in photoprotection, like the LHC-like and the photosystem II subunit S (PSBS). The evolution of this complex superfamily has long remained elusive, partially due to previously missing families. 相似文献192.
193.
194.
Yan-Hong He Guo-Gui Ning Ya-Lin Sun Yan Hu Xing-Yu Zhao Man-Zhu Bao 《Molecular breeding : new strategies in plant improvement》2010,26(1):19-29
A male sterile line was isolated in marigold (Tagetes erecta L.) and cytological analysis determined this to be a novel genic male sterility trait (Tems). Through the use of amplified fragment length polymorphisms (AFLPs) and bulked segregant analysis (BSA), tightly linked
markers of Tems were identified with a view towards a map-based cloning strategy. It was found that spontaneous homeotic conversion of floral
organs was the underlying cause of the male sterility in this marigold line. Thus, petals of male sterile plants resembled
sepal-like structures and the stamens were partially converted to styles, although without the full characteristics or function
of the true style organs. We have constructed a fine marker-based map for the Tems gene. This is intended to provide a tool for marker assisted selection (MAS) strategies in hybrid breeding and map-based
cloning strategies for the male sterility locus. We discuss the significance of this spontaneously derived genic male sterility
trait relating to the homeotic conversion of floral organs in marigold. 相似文献
195.
Andrew Leask 《Journal of cell communication and signaling》2010,4(2):109-110
The role of CCN proteins in vivo is only just becoming understood. A prototypical member of the CCN family, CCN3 suppresses proliferation. In a study in press, Shimoyama and colleagues show that mice lacking CCN3 have a hyperproliferative response to vascular injury. These data, along with other recent observations, suggest that CCN3 may represent a novel therapy for hyperproliferative diseases. 相似文献
196.
In this paper we propose that the internal bracketing of a word with more than two morphemes is reflected in the phonetic implementation. We hypothesize that embedded forms show more phonetic reduction than forms at higher structural levels (‘Embedded Reduction Hypothesis’). This paper tests the prediction of the Embedded Reduction Hypothesis with triconstituent compounds. The analysis of the durational properties of almost 500 compound tokens shows that there is a lengthening effect on the non-embedded constituent, and a shortening effect on the adjacent embedded constituent. Yet, this predicted effect of embedding interacts with other lexical factors, above all the bigram frequency of the embedded compound. At a theoretical level, these effects mean that the durational properties of the cross-boundary constituents are indicative of the hierarchical structure and of the strength of the internal boundary of triconstituent compounds. Hence, morphological structure is reflected in the speech signal. 相似文献
197.
198.
199.
200.
Eric Delson 《Journal of Mammalian Evolution》2007,14(3):198-199